Warpips is a tug of war strategy game which basically means players fight by sending units through a horizontal lane towards the enemy. Most of the fighting itself is done by the units automatically so this genre is more on the casual side of strategy.
On that note, I think Warpips is one of the best ones I've played so far, I like the military theme, the presentation is charming and there are plenty of different units to play with including infantry, structures, vehicles, artillery, etc. There's a lot of meat on it for a casual game.